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See detailSafety-aware Location Privacy in VANET: Evaluation and Comparison
Emara, Karim Ahmed Awad El-Sayed UL

in IEEE Transactions on Vehicular Technology (in press)

VANET safety applications broadcast cooperative awareness messages (CAM) periodically to provide vehicles with continuous updates about the surrounding traffic. The periodicity and the spatiotemporal ... [more ▼]

VANET safety applications broadcast cooperative awareness messages (CAM) periodically to provide vehicles with continuous updates about the surrounding traffic. The periodicity and the spatiotemporal information contained in these messages allow a global adversary to track vehicle movements. Many privacy schemes have been proposed for VANET, but only few schemes consider their impact on safety applications. Also, each scheme is evaluated using inconsistent metrics and unrealistic vehicle traces, which makes comparing the actual performance of different schemes in the wild more difficult. In this paper, we aim to fill this gap and compare different privacy schemes not only in terms of the privacy gained but also their impact on safety applications. A distortion-based privacy metric is initially proposed and compared with other popular privacy metrics showing its effectiveness in measuring privacy. A practical safety metric which is based on Monte Carlo analysis is then proposed to measure the QoS of two safety applications: forward collision warning and lane change warning. Using realistic vehicle traces, six state-of-the-art VANET privacy schemes are evaluated and compared in terms of the proposed privacy and safety metrics. Among the evaluated schemes, it was found that the coordinated silent period scheme achieves the best privacy and QoS levels but fully synchronized silence among all vehicles is a practical challenge. The CAPS and CADS schemes provide a practical compromise between privacy and safety since they employ only the necessary silence periods to prevent tracking and avoid changing pseudonyms in trivial situations. [less ▲]

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See detailContext-based Pseudonym Changing Scheme for Vehicular Adhoc Networks
Emara, Karim Ahmed Awad El-Sayed UL; Woerndl, Wolfgang; Schlichter, Johann

E-print/Working paper (2016)

Vehicular adhoc networks allow vehicles to share their information for safety and traffic efficiency. However, sharing information may threaten the driver privacy because it includes spatiotemporal ... [more ▼]

Vehicular adhoc networks allow vehicles to share their information for safety and traffic efficiency. However, sharing information may threaten the driver privacy because it includes spatiotemporal information and is broadcast publicly and periodically. In this paper, we propose a context-adaptive pseudonym changing scheme which lets a vehicle decide autonomously when to change its pseudonym and how long it should remain silent to ensure unlinkability. This scheme adapts dynamically based on the density of the surrounding traffic and the user privacy preferences. We employ a multi-target tracking algorithm to measure privacy in terms of traceability in realistic vehicle traces. We use Monte Carlo analysis to estimate the quality of service (QoS) of a forward collision warning application when vehicles apply this scheme. According to the experimental results, the proposed scheme provides a better compromise between traceability and QoS than a random silent period scheme. [less ▲]

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See detailPrivacy-Preserving Proximity Services
Haus, Michael; Emara, Karim Ahmed Awad El-Sayed UL; Ott, Joerg

Report (2016)

In the last years, the paradigm of personal computing changed drastically, moving away from stationary PCs and heavyweight laptops to mobile devices. This change is based on the ubiquity of mobile ... [more ▼]

In the last years, the paradigm of personal computing changed drastically, moving away from stationary PCs and heavyweight laptops to mobile devices. This change is based on the ubiquity of mobile interconnected devices leading to great opportunities for services that utilize location, such as navigation or communication with nearby friends. Location-based Services (LBS) are widely used based on a centralized architecture and absolute GPS positions. We focus on Proximity-based Services (PBS) based on peer-to-peer architecture to detect what is around us. In addition, we provide further insights about which data are potentially useful to create meaningful proximity information. Many LBS and PBS achieve their functionality without advanced privacy protection mechanisms. However, mobile data especially location data is sensitive, because adversaries can infer whereabouts of mobile users. Moreover, the uniqueness of human mobility traces is high yielding to a high identification rate of individual users. Therefore, we review the most recent literature in the domain of private proximity testing including attack models. [less ▲]

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See detailPoster: PREXT: Privacy Extension for Veins VANET Simulator
Emara, Karim Ahmed Awad El-Sayed UL

Poster (2016)

Preserving location privacy is an important aspect in vehicular ad-hoc networks. Although location privacy is thoroughly studied in the past decade, it is usually skipped in VANET simulators. In this ... [more ▼]

Preserving location privacy is an important aspect in vehicular ad-hoc networks. Although location privacy is thoroughly studied in the past decade, it is usually skipped in VANET simulators. In this paper, we propose a location privacy extension, PREXT, for Veins framework. Currently, PREXT supports seven privacy schemes of different approaches including silent period, context-based and cryptographic mix-zone. It can be also easily extended to include more schemes. It includes adversary modules that can eavesdrop vehicle messages and track their movements. This adversary is used in measuring the gained privacy in terms of several popular metrics such as entropy, traceability and pseudonym usage statistics. We utilize this extension to compare among different schemes in an urban scenario. [less ▲]

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See detailCAPS: Context-Aware Privacy Scheme for VANET Safety Applications
Emara, Karim Ahmed Awad El-Sayed UL; Woerndl, Wolfgang; Schlichter, Johann

in ACM Wisec 15 (2015)

Preserving location privacy in vehicular ad hoc networks (VANET) is an important requirement for public accep- tance of this emerging technology. Many privacy schemes concern changing pseudonyms ... [more ▼]

Preserving location privacy in vehicular ad hoc networks (VANET) is an important requirement for public accep- tance of this emerging technology. Many privacy schemes concern changing pseudonyms periodically to avoid linking messages. However, the spatiotemporal information con- tained in beacons makes vehicles traceable and the driver’s privacy breached. Therefore, the pseudonym change should be performed in a mix-context to discontinue the spatial and temporal correlation of subsequent beacons. Such mix- context is commonly accomplished by using a silence period or in predetermined locations (e.g., mix-zone). In this pa- per, we propose a location privacy scheme that lets vehicles decide when to change its pseudonym and enter a silence period and when to exit from it adaptively based on its con- text. In this scheme, a vehicle monitors the surrounding vehicles and enters silence when it finds one or more neigh- bors silent. It resumes beaconing with a new pseudonym when its actual state is likely to be mixed with the state of a silent neighbor. We evaluate this scheme against a global multi-target tracking adversary using simulated and realistic vehicle traces and compare it with the random silent period scheme. Furthermore, we evaluate the quality of service of a forward collision warning safety application to ensure its applicability in safety applications. We measure the quality of service by estimating the probability of correctly identify- ing the fundamental factors of that application using Monte Carlo analysis. [less ▲]

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See detailOn Evaluation of Location Privacy Preserving Schemes for VANET Safety Applications
Emara, Karim Ahmed Awad El-Sayed UL; Woerndl, Wolfgang; Schlichter, Johann

in Computer Communications (2015), 63(1), 11--23

Location privacy in vehicular ad hoc networks has gained considerable attention in the past few years. The majority of studies concern changing pseudonyms to prevent linking messages of the same pseudonym ... [more ▼]

Location privacy in vehicular ad hoc networks has gained considerable attention in the past few years. The majority of studies concern changing pseudonyms to prevent linking messages of the same pseudonym. However, the precise spatiotemporal information included in beacons (i.e., timestamp, position, speed and heading) makes them vulnerable to tracking even if they are completely anonymous. One of the most important issues in designing location privacy scheme is to preserve the quality of service of the application. This issue is more significant for safety applications, since they require precise and frequent state updates. Thus, it is crucial to consider this trade-off between location privacy and quality of service of the safety application when designing and evaluating privacy schemes. In this paper, we propose a methodology to measure both the protection level of a privacy scheme and its impact on safety applications. We employ an empirical vehicle tracker to measure the effectiveness of a privacy scheme in terms of a number of confusions. We also measure its impact on a safety application by estimating the probability of correctly identifying the fundamental factors of that application using Monte Carlo analysis. Further, we propose an obfuscation privacy scheme which perturbs position and beacon frequency. Finally, we apply our methodology to evaluate the proposed scheme and compare it with the popular privacy scheme, random silent period. [less ▲]

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See detailPOSTER: Context-adaptive user-centric privacy scheme for VANET
Emara, Karim Ahmed Awad El-Sayed UL; Woerndl, Wolfgang; Schlichter, Johann

in Lecture Notes of the Institute for Computer Sciences, Social-Informatics and Telecommunications Engineering, LNICST (2015)

Vehicular adhoc network allows vehicles to exchange their information for safety and traffic efficiency. However, exchanging information may threaten the driver privacy because it includes spatiotemporal ... [more ▼]

Vehicular adhoc network allows vehicles to exchange their information for safety and traffic efficiency. However, exchanging information may threaten the driver privacy because it includes spatiotemporal information and is broadcast publicly on a periodical basis. In this paper, we propose a context-adaptive privacy scheme which lets a vehicle decide autonomously when to change its pseudonym and how long it should remain silent to ensure unlinkability. This scheme adapts dynamically based on the density of the surrounding traffic and the user privacy preferences. According to the experimental results, the proposed scheme demonstrates a significant reduction in traceability with a better quality of forward collision warning application compared with the random silent period scheme. \textcopyright Institute for Computer Sciences, Social Informatics and Telecommunications Engineering 2015. [less ▲]

Detailed reference viewed: 33 (4 UL)